object Main extends App {
  val a: String = scala.io.StdIn.readLine()
  val b: String = scala.io.StdIn.readLine()

  val aIntOpt = if (a.matches("^(?!.0)[0-9]{1,5}") && a.toInt <= 12345) {
    Some(a.toInt)
  } else {
    None
  }

  val bIntOpt = if (b.matches("^(?!.0)[0-9]{1,5}") && a.toInt <= 12345) {
    Some(b.toInt)
  } else {
    None
  }

  val ans = for {
    a <- aIntOpt
    b <- bIntOpt
  } yield a + b

  println(if (ans.nonEmpty) "OK" else "NG")

}